JP3766015B2 - Overrun detection method for variable wing turbo system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an overrun detection direction of a variable wing turbo system.
[0002]
[Prior art]
In variable wing turbo systems used as supercharging means for engines, air flow meters, boost pressure sensors, atmospheric pressure sensors, accelerator sensors, brake sensors, engine rotation sensors, etc. are used to perform control aimed at more efficient points. For optimal control of the engine and turbo system. Therefore, there is a high risk of falling into an overrun in which the turbine rotational speed abnormally increases due to a system abnormality or the like, and it is necessary to monitor the turbine rotational speed to avoid the overrun and protect the system.
[0003]
For this reason, in the past, the turbine rotation speed was estimated based on the boost pressure to avoid overrun. However, if the turbine overrun was simply estimated based on the boost pressure, the rotation speed would be There is a problem that the detection accuracy is not so high.
[0004]
In order to simply detect and avoid overrun, it is conceivable to directly monitor the turbine speed using a rotation sensor or the like. However, in this case, since it is necessary to add a rotation sensor, the cost is high, and the use environment is extremely severe, such as the necessity to attach the rotation sensor to a turbine that is exposed to high temperatures. It was almost impossible to obtain a rotation sensor.
[0005]
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and detects an overrun using an output signal of an existing sensor provided as a monitoring means for a variable blade turbo system without newly adding a rotation sensor or the like. It is an object of the present invention to provide a novel detection method that can be performed.
[0006]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides an air cleaner based on an intake air amount, an atmospheric pressure, and a boost pressure obtained from signals of an air flow meter, an atmospheric pressure sensor and a boost pressure sensor provided in a variable blade turbo system. Calculate pressure loss and intercooler pressure loss. Further, the pressure ratio before and after the compressor is obtained by correcting the atmospheric pressure and the boost pressure by the air cleaner pressure loss and the intercooler pressure loss. Then, when the intake air amount is equal to or greater than the overrun air amount derived from the intake air amount and the pressure ratio, it is determined that the overrun has occurred.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a conceptual diagram of a variable blade turbo system to which an overrun detection method according to the present invention is applied. An air flow meter 4 is provided in an intake passage 3 for supplying air from an air cleaner 1 to a compressor 2 of the variable blade turbo system. Air discharged from the compressor 2 is guided to an intake manifold 6 of an engine (not shown) via an intercooler 5.
[0008]
Further, a boost pressure sensor 7 is provided in the intake manifold 6, and output signals of the boost pressure sensor 7 and the air flow meter 4 are supplied to the control unit 8. The output signal of the atmospheric pressure sensor 9 is supplied to the control unit 8. As in the prior art, the variable wing turbo system is optimally controlled in response to the operating state of the engine by supplying output signals from an engine rotation sensor, an accelerator sensor, a brake sensor, etc. (not shown). .
[0009]
Here, in the present invention, an overrun of the turbine is detected based on output signals of the air flow meter 4, the boost pressure sensor 7 and the atmospheric pressure sensor 9.
[0010]
2 is a logic diagram illustrating the overrun detection process performed in the control unit 8. The air cleaner pressure loss PAC and the intercooler pressure loss PIC are obtained based on the intake air amount AIR derived from the output signal of the air flow meter 4. FIG. Each of these pressure losses PAC and PIC is performed by reading from a one-dimensional map of the intake air amount AIR.
[0011]
Next, the inlet pressure P1 of the compressor 2 is obtained by subtracting the air cleaner pressure loss PAC from the atmospheric pressure PATM calculated based on the output signal of the atmospheric pressure sensor 9, while the boost pressure PIM calculated based on the output signal of the boost pressure sensor 7 is obtained. Then, the intercooler pressure loss PIC is added to obtain the outlet pressure P2 of the compressor 2, and the outlet pressure P2 is divided by the inlet pressure P1 to calculate the pressure ratio πC of the compressor 2.
[0012]
Further, the overrun air amount AIROR at the pressure ratio πC is read from an equal turbine map mounted on the control unit 8. Subsequently, the overrun air amount AIROR and the actual intake air amount AIR based on the output signal of the air flow meter 4 are compared.
[0013]
As a result of the comparison, when the intake air amount AIR is less than the overrun air amount AIROR, a determination signal indicating that it is not overrun is output, and when the intake air amount AIR is equal to or greater than the overrun air amount AIROR, the turbine is overrun. Judgment is made and a judgment signal to that effect is output. Therefore, by monitoring the determination signal, it is possible to accurately know whether or not the turbine is overrun without using a rotation sensor or the like that is used in a severe environment.
[0014]
The equal turbine map used for reading the overrun air amount AIROR is an equal turbine rotation speed map represented by, for example, a pressure ratio πC and an intake air amount AIR as shown in FIG. 3, and corresponds to the pressure ratio πC. The minimum air amount in the overrun rotation region is output as the overrun air amount AIROR.
[0015]
Therefore, according to the present embodiment, output signals from the air flow meter 4, boost pressure sensor 7, atmospheric pressure sensor 8, and the like provided in the engine with the variable blade turbo system are simply processed by the control unit 8, and the turbine Since the overrun can be accurately detected, there is no need to directly monitor the rotational speed of the turbine using a rotation sensor or the like, and the control reliability of the variable blade turbo system is increased.
[0016]
In the above embodiment, the intake air amount AIR, the boost pressure PIM, and the atmospheric pressure PATM are calculated based on the output signals of the air flow meter 4, the boost pressure sensor 7, and the atmospheric pressure sensor 8. In short, the intake air amount is calculated. A turbine overrun may be calculated using AIR, boost pressure PIM, and atmospheric pressure PATM, and the specific structure and mounting position of each sensor are not limited to those of the embodiment.
[0017]
【The invention's effect】
As is clear from the above description, the present invention can detect the turbine overrun with high accuracy based on the intake air amount, the boost pressure and the atmospheric pressure. Thus, the control reliability of the variable blade turbo system can be increased.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram of a variable wing turbo system to which an overrun detection method according to the present invention is applied.
FIG. 2 is a logic diagram illustrating an overrun detection process performed in the control unit shown in FIG. 1;
FIG. 3 is a conceptual diagram of an equal turbine rotation speed map indicated by a pressure ratio πC and an intake air amount AIR.
[Explanation of symbols]
1 Air cleaner 2 Compressor 3 Suction passage 4 Air flow meter 5 Intercooler 6 Intake manifold 7 Boost pressure sensor 8 Control unit 9 Atmospheric pressure sensor

Claims (1)

The air cleaner pressure loss ( AIR) based on the intake air amount (AIR) supplied to the compressor (2) of the variable blade turbo system, the atmospheric pressure (PATM), and the boost pressure (PIM) detected from the intake manifold (6) of the engine ( PAC) and intercooler pressure loss (PIC) are calculated, and the atmospheric pressure (PATM) and boost pressure (PIM) are corrected by air cleaner pressure loss (PAC) and intercooler pressure loss (PIC) , and the pressure ratio before and after the compressor (πC) the calculated variable that the intake air amount (aIR) is characterized in that it determined to be overrun when it the inhalation air amount (aIR) and overrun amount of air derived from the pressure ratio (πC) (AIROR) or Overrun detection method for wing turbo system.

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